Physicochemical changes in erythrocyte membranes during cold storage in the presence of progesterone

Red cells were stored for 42 days, with and without added progesterone, and at 14-day intervals stroma was prepared from these red cells for analysis by various physicochemical methods. Progesterone appears to bind to the erythrocyte membrane proteins, causing a change in their structure which “locks” them into a stabilized state that is more or less constant for at least 28 days, then starts to wear off or dissociate.